When to use singleton pattern in php

Why use PHP singleton mode?

1. The application of PHP is mainly in database applications, so there will be a large number of database operations in an application. If you use singleton mode, you can Avoid a large number of resources consumed by new operations.

#2. If a class is needed to globally control certain configuration information in the system, it can be easily implemented using the singleton mode. (Recommended learning: PHP programming from entry to proficiency)

3. In one page request, it is easy to debug, because all the code (such as database operation class db) Concentrated in one class, we can set hooks in the class to output logs, thereby avoiding var_dump and echo everywhere.

<?php
header("Content-Type: text/html; charset=UTF-8");
class Singleton{
//保存类的实例
private static $_instance;
private function __construct(){
echo "This is a Constructed method;";
}
//防止对象被克隆
public function __clone(){
trigger_error(&#39;Clone is not allow !&#39;,E_USER_ERROR);
}
public static function getInstance(){
if(!(self::$_instance instanceof self)){
self::$_instance=new self;
}
return self::$_instance;
}
public function test(){
echo &#39;调用方法成功&#39;;
}
}
//正确的调用方法
$singleton = Singleton::getInstance();
$singleton->test();
$singleton_clone = clone $singleton;
?>

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